1. Field of the Invention
This application relates generally to building ventilation and specifically to roof ventilation.
2. Description of the Related Art
Energy efficiency is a serious consideration in new home design. New homes require ways to minimize energy requirements to maintain comfortable living spaces. One of the most common energy losses in a home is due to heat transfer through the attic. In warm climates, heat builds up in the attic from solar energy incident on the roof. In colder climates, moisture builds up in the attic, robbing the insulation of much of its R value. Early efforts at minimizing the effects of heat and/or moisture build-up focused on insulation between the living space and the attic. Gable vents and dormer type passive ventilation systems have been incorporated to ventilate the attic. U.S. Pat. No. 6,050,039 to O'Hagin describes one such camouflaged passive ventilation system.
Ventilation systems have been provided to enhance the insulation of a roof. Such ventilation systems remove heat and/or moisture build-up in the attic, thus minimizing energy losses due to heat transfer through the attic. Typical roof ventilation systems have included a combination of roof vents and roof cover materials, such as tiles. The roof vents conduct airflow between the regions above and below the roof.
Recently, it has been shown that providing an airspace or air layer below the roof cover materials (e.g., tiles, shingles, etc.) but above the sheathing (e.g., a plywood or metal roof deck) improves the energy efficiency of the building, even if the air layer is not ventilated. If the airspace is ventilated (i.e., in fluid communication with the attic and the building exterior), energy efficiency is further improved.
Additionally, a roof can include a radiant barrier to enhance the insulation. The radiant barrier layer enhances the insulation by reflecting radiant heat away from the roof. Traditionally, buildings with radiant barrier layers have been used as a means to simultaneously reflect radiant heat away from the roof and trap heat within the building. However, buildings with radiant barriers still have heat or moisture build-up in the attic. What is needed is an improved ventilation system which minimally detrimentally affects the appearance of a building design and is applicable to various types of roofs, while offering low installation costs relative to other ventilation systems.